Lubricating compositions



LUBRICATING coMPosiTroNs Cornelis Stillebroer, Delft, and Johan Leonardvan der Minne, Amsterdam, Netherlands, assignors to Shell DevelopmentCompany, New York, N. Y., a corporation of Delaware No Drawing.Application November 15, 1954, Serial No. 469,035

Claims priority, application Netherlands November 24, 1953 7 Claims.(Cl. 252-336) This invention relates to water-in-oil emulsions suitablefor lubricating engines, particularly low speed diesel engines operatingon high sulfur fuels.

Although it is known in the art that emulsions are useful as coolantsand lubricants in metal working operations and as rust and corrosioninhibitors, their use as engine lubricants is limited. Under engineoperating conditions, emulsions generally lack desired lubricity,causing wear and corrosion.

It has now been discovered that engines can be lubricated safely andefficiently by using a water-in-oil emulsion consisting essentially offrom about to about 40% (preferably between 10% and about 30%) of waterand from about 95% to about 60% (preferably between about 90% and about70%) of a lubricating oil, said emulsion also containing, in the aqueousphase of the emulsion, a water-soluble salt of a divalent metal in anamount of at least 0.25 gram mols per liter, based on the aqueous phase,and preferably at least 0.5 gram mols per liter, and even higher, e. g.,2.5 gram mols per liter.

The cationic portion of the salt must be a divalent metal such as thealkaline earth metals, including calcium, barium, strontium, magnesium,as well as zinc, cadmium, nickel, lead, copper and iron; the preferredmetals are calcium, barium, strontium and magnesium. The anionic portionof the salt is selected from anions of particular classes of inorganicand organic acidic compounds. Generally, these anionic radicals are suchthat with the above metals (cationic) they form water-soluble salts. Ofthe inorganic acidic compounds, the preferred ones are the weakerinorganic acids. Of the organic acidic compounds the preferred ones are:the lower fatty acids, e. g., formic, acetic and propionic acids;substituted lower fatty acids, such as hydroxy-, ketoand amino-acetic,propionic and butyric acids; polycarboxylic acids having not more than10 carbons in the molecule, such as oxalic, maleic, and succinic acids;as well as aromatic acids. such as salicylic acid, mandelic acid,anthranilic acid, phthalic acid, and mixtures thereof. Specific examplesof salts suitable for use in Water-in-oil emulsion lubricants of thisinvention includes the zinc, calcium, barium and magnesium nitrites,nitrates, chromates, sulfates, formates, acetates, propionates,aminoacetates, alpha-aminopropionates, glycol- 4 ates, oxalates,succinates, salicylates, phthalates, mandelates, anthranilates, andmixtures thereof.

The water-in-oil emulsions are generally prepared by incorporating oneor more emulsifiers. Any emulsifier may be used which is suitable foremulsifying an aqueous phase in an oil phase, provided no harmfulsubstances are formed from the emulsifier during the combustion processin the engine. Suitable emulsifiers are esters of polyhydric alcohols,such as the monoesters of glycerol with higher fatty acids, e. g.,glycerol mono-oleate, glycerol mono-stea'rate, glycerolmono-ricinoleate, diethylene glycol mono-laurate, diethylene glycolmono-oleate, diethylene glycol mono-stearate and sorbitan mono-oleate;as

well as alkylene oxide derivatives of such partial esters such asreaction products of sorbitan mono-oleate and alkylene oxides, such asethylene oxide; polyvalent metal salts of fatty acids, napthenic acidsor organic sulfonic acids or resin acids; such as Ca, Ba, Zn and Alstearate, oleate, naphthenate, petroleum sulfonate and abietate;lanolin, oxidized vegetable oils and lecithin. A combination of two ormore emulsifiers may also be used. Especially stable emulsions areobtained by the combined use of a polyvalent metal salt, e. g., a basiccalcium salt of an oil-soluble petroleum-sulfonic acid, and a polyvalentmetal salt, e. g., a basic calcium salt of an aromatic hydroxycarboxylicacid substituted by one or more alkyl groups with 12 or more carbonatoms, e. g., hexadecylsalicylic acid.

The water-in-oil emulsions may be prepared in a simple way by adding theaqueous salt solution to the oil containing the emulsifier(s), afterwhich the mixture is stirred and preferably further homogenized, e. g.,by passing the emulsion through a gear pump. By means of the lattertreatment the average size of the particules dispersed in the emulsioncan be considerably decreased, particularly to a size of 2 microns orless.

The lubricating oil used to form the water-in-oil emulsion of thisinvention can be any natural or synthetic hydrocarbonaceous oil havinglubricating properties. Thus, the base may be a hydrocarbon oil of wideviscosity range, e. g., SUS at 100 F. to SUS at 210 F. The hydrocarbonoils may be blended with fixed oils such as castor oil, lard oil and thelike, and/or with synthetic lubricants such as polymerized olefins,organic esters of polybasic organic and inorganic acids, e. g., di-Z-ethylhexyl sebacate, dioctyl phthalate, trioctyl phosphate; polymerictetrahydrofuran; polyalkyl silicone polymers, e. g., dimethyl siliconepolymer and the like.

Representative mineral lubricating oils which have been utilized inevaluating the utility of the present additives had the followingspecifications:

I II

Gravity, API-" Pour Point, F Flash, COO, F

Viscosity, SUS at 210 F.

Min. 26.5.

Min. 24.5.

Viscosity Index Water-in-oil emulsions of this invention areparticularmally used in marine installations. Corrosion, Wear andfouling of such engines is aggravated because contaminants such as dirt,water and deterioration products from cheap grades of fuel (high insulfur content) normally used to operate such equipment, can easilyenter the lubrication system.

A cheap grade of hydrocarbon fuel containing substantial amounts ofnaturally occurring sulfur is used in low speed diesel engines becauseof economy and because it has been observed that sulfur-containingpetroleum fuels have enhanced ignition properties. However, theseadvantages are countered by the corrosive nature of such fuels whichresults in excessive Wear.

By the expression high sulfur fuels as used herein is meant those fuelswhich contain sulfur, either in the free or combined state, to theextent of from about 0.1% to about 5.0% by weight and preferably between0.5% and 3.5%, calculated as elemental sulfur, though even more sulfurmay be present, and include petroleum fuel oil or various distillate andresidual oils and the like.

Various means have been tried to overcome the detrimental effects ofhigh sulfur fuels on engine operations. Thus, the Chandler patent, U. S.2,673,145 proposes to add to high sulfur fuels various metallicinorganic salts in order to reduce the corrosive effects caused by thepresenceofsulfur in the fuel. Although thismethod iseifec tive, itsufiers from certain disadvantages in its practical application.However, it has been found that engine efficiency can beincr eased 5'to'50 times'over theifilhandler method or similar methods bylubricatingengines operatingz on high sulfur fuels with water-in-oilemulsions .of this invention.

The invention will be further illustrated by the following examples.

A'number of'comparative: tests were. carried out in a 20 horsepowerdiesel two-stroke engine. The engine was run'atta speed of600'revolutionsaminute.

'In eachof the tests the fuel was a gas oil with a sulfur content of 1%by weight, calculated'as elementalsulfur. A lubricating oil distillatewith a viscosity of 42-centistoke at 60 *C., extracted according to theEdeleanu process, wasused as-the lubricating oil base in-each of thetests. In order to prepare the water-in-oil emulsions, glycerolinono-oleate was added to this lubricating oil as anemulsifier in aquantity of 2% by weight, calculated on the oil, after which an aqueoussalt solution was added t'o theoil in a quantity of parts-by weight to100 parts by weightof the lubricating oil containing the'emulsifier.After the emulsification had been efiected by stirring, the-emulsion'was passed twice through a gear pump. Thus, by using various salts,diiferent water-in-oil-emulsions were obtained which were used forlubricating the cylindcr'in'the-diesel two-stroke engine referred to.

In 'each test the engine was run for 8 hours, after which it wasinspected. Two successive tests with the lubricating oil base and twosuccessive tests with a waterin-oil emulsion were carried outalternately.

The effect .of the various water-in-oil emulsions examined, as comparedwith the lubricating oil base,'was measured by determining the decreasein weight of the piston rings. This decrease in weight is a measure ofthe wear. The wear occurring with the use of the various water-in-oilemulsions is expressed as a percentage of the wear occurring when thelubrication is effected with the lubricating oil base as such, i. e.,the latter wear is arbitrarily put at 100.

The results of the tests are shown in the following Table I. In thisconnection it should be further observed that with the use of leadacetate its aqueous solution was mixed with the lubricating oilbase in aquantityof parts by weight (instead of 10 parts by weight, as in theother cases) to 100 parts by weight of the lubricating oil basecontaining the emulsifier.

Table l gonceitr'ii Type. of saltin the emulsifier Ion 0 5a r so u ionrs sum or i t 3,3 g Fi t R ind meal/1 piston 0! piston ring rings Leadacetate... 0. 56 85 80 Zincacetate 1. 13 80 6O Magnesium acetate. 1. 1355 60 Barium acetate.. 1. 13 50 Calcium acetate 1. 13 .40 Calciumoi-mate... 1. 13 55 Calcium nitrate. 1. 13 65' 55 Calcium nitrite .1. 1345 Magnesium sulfate 1.13 55 6O Magnesium chlorid 1. 13 r 90 60 Sodiumacetate. .2. 25 ,110 Aluminum acetate 0. 350 300 Aluminum chloride.. 0.7 .600 500 IBOSPhOIiC acid.

13 rea Acetic acid 1. 13 135 Sulfuric acid 1-13 130 Potassiumchroma-to. 1. 13 120 170 Hydrochloricacid. .1. 13 110. 105 Calciumnitrite. 0. 1 120 with the use of water-in-oil emulsions of which theaqueous phase contains no salt, or a-sodium or'potassium criticalminimum value poor results areobtained. 'Reference ismade to lines 8 and20 in Table I.

In another test a two-stroke 350 H. P. marinediesel engine operating ata speed of 250 revolutionsa minute was lubricated with an emulsion ofthis invention. and the results were as follows:

The motor fuel used was a bunker oil with a sulfur content of 3.2% byweight, calculated as. elemental sulfur. This fuel had aConradsonCarbon-number of 11%.

As the emulsion, a water-in-oil emulsion was used, 70% byweight of whichconsisted of the oil base containing the emulsifier and 30% by weight ofan aqueous 25 per cent calcium acetate solution. The oil base was'thesame as-that used in Example 1. The emulsifier was a combination of abasic calcium'salt of .an oil-soluble petroleum-'sulfonic acid with amixture of basic calcium compounds of'salicylic acids substituted by astraightchain alkylgroup having 14-18 carbon atoms. Each of the twocomponents of the mixture of emulsifiers .was

used'ina quantity corresponding to 0.05% by weight .of

Ca, calculated on the oil base.

The efiect of the use of the watcr-in-oil emulsion, as compared to theoil base as such in lubricating the cylinder was determined ina mannersimilar to that of the previous example by'measuringthe loss in weightof the firstpiston ring and that of'the remaining piston rings, while atthe same time ther'ouling of the cylinder wall was determined. For thispurpose, a test was carried out with the water-in-" oil emulsion and atest with the oil base as such. The duration 'of each test was 172'h0urs.

With the use of the emulsion of the aqueous calcium acetate solution inthe oil base it was foundthat the loss in weight of the first'pistonring was only 25% of the loss inweight'which occurred in usingthe oilbase as such, while the loss in weight of the remaining piston rings.withthe use of the emulsion was only 12% of theloss in. weight occurringwiththe use of the oil baseas. such. With the useof the emulsion thewear of the cylinder wall was only 10% of the wear which occurredwith-the use of the oil base. In-this case the engine was operatedfor400 hours.

With the use of the water-in-oil .emulsion there was also only slightfouling-of the cylinder wall. Moreover, the slight deposits .in thecylinder space were brittle in structure, and easily removed whereaswith lubricating oil fouling on cylinder wall was .excessiveand.diflieult to remove.

I.During the-test the emulsion was found to remainstable intheilubricator. 1

Similar engine results can be'obtained using water-inoil'emulsionsofthis invention as the lubricant for engines, operating on fuelscontaining from 1% to 3% sulfur in which the aqueous phase of theemulsion contains from- .about 0.5 to about '2.5 gram mols per liter ofcalcium,

tially of a water-in-oil emulsion consisting essentially of from 5% to40% by weight of water and from 60% to 95% of a mineral lubricating oil,said water phase of the emulsion containing in solution at least 0.25gram mols per liter of a water-soluble salt of a divalent metal.

2. A lubricating composition for lubrication of internal combustionengines operating with high sulfur hydrocarbon fuels, said lubricatingcomposition consisting essentially of a water-in-oil emulsion consistingessentially of from 5% to 40% by weight of water and from 60% to 95% ofa mineral lubricating oil, said water phase of the emulsion containingin solution from 0.5 to 2.5 gram mols per liter of a water-solublealkaline earth metal salt.

3. The composition of claim 2 wherein the salt is calcium acetate.

References Cited in the file of this patent UNITED STATES PATENTS LazarFeb. 11, 1941 Brown June 29, 1942

1. A LUBRICATING COMPOSITION FOR LUBRICATION OF INTERNAL COMBUSTIONENGINES OPERATING WITH HIGH SULFUR HYDROCARBON FUELS, SAID LUBRICATINGCOMPOSITION CONSISTING ESSENTIALLY OF A WATER-IN-OIL EMULSION CONSISTINGESSENTIALLY OF FROM 5% TO 40% BY WEIGHT OF WATER AND FROM 60% TO 95% OFA MINERAL LUBRICATING OIL, SAID PHASE OF THE EMULSION CONTAINING INSOLUTION AT LEAST 0.25 GRAM MOLS PER LITER OF A WATER-SOLUBLE SALT OF ADIVALENT METAL.